the past years I have heard the words 'climate change' or 'global warming'
whispered in terror at an exponentially increasing rate. Some of my acquaintances
speak as though they were already half-dead from overheating. Later they
recount the holiday spent in Bali frying on a beach at 40°C and then
how dangerous an extra 1°C on top of 20°C would be for the population
of the U. K.. The manifest fact that more and more exotic species of plant
are appearing in garden centres up and down the country is often cited
as incontrovertible evidence of climate change. If to this we add the
encouraging voices of TV's 'instant gardeners' and the popping up of large
exotic botanical specimens in gardens where previously the rose and the
lupin reigned supreme the matter appears to be settled: soon we will have
it even hotter than Bali. The BBC's 'severe weather warnings' every time
a breeze or showers are on the way seems to do little to allay the fears
of much of the population.
obviously consider that selling 'plants for a changing climate' or 'kits
for a waterless garden' to be a good a good way to boost sales. Best of
luck to them, although many 'climate change believers' suggest that not
droughts but torrential downpours will be the norm. More worrying for
gardeners perhaps is a report in The Daily Telegraph (15 January
2011) that the RHS has joined in the fray. The paper reports that the
RHS is advising gardeners to stop watering their gardens, that lawn fertilizers
are 'environmentally unsustainable' and that more trees should be planted
in order to 'suck up carbon dioxide'. This all seems a long way removed
from advising on how best to care for plants. I am glad that I chucked
in my membership some years ago because the chillingly cold truth is that
rigorous scientific evidence for man's effect on global temperature rise
is simply not available. The only sure thing is that temperatures have
been very much higher in the past - evidenced by frozen mammoth remains
surfacing in Siberia as the permafrost retreats - and that the role of
carbon dioxide as a 'greenhouse gas' is dwarfed many times over by atmospheric
water vapour whose 'greenhouse effect' is enormous. I am mentioning all
this as an introduction to explaining why I think we observe more and
more 'exotics' in British gardens.
and most obvious reason for the explosion of exotics in U. K. gardens
is that gardeners, amateur gardeners in particular, are becoming more
knowledgeable. Books, TV programmes and now the internet have made the
average gardener both more savvy and more adventurous. Think of the late
Christopher Lloyd, Will Giles, Abbotsbury and the jungle at Heligan. Where
previously a timid gardener might have poked an Agave into a
heavy clay soil in a shady corner and left it to fend for itself today
he will seek out a prime position for it on a sunny south-facing bank
and give it the best he can in terms of well-drained soil and shelter.
Not all books, TV programmes and internet pages are correct however, and
it does require an extra degree of finesse of judgement to distinguish
between the well-informed expert and the populist dilettante. Many very
cold-tolerant plants have the very reverse reputation and it is only recently
that this and similar information is beginning to trickle through to the
A few examples
here would be in order. The ‘Great Bible of Gardeners’, the
RHS Encyclopedia of Garden Plants (1966 edition) is most certainly not
a book written by dilettantes but it lists Agave americana and
A. parryi as tolerant of temperatures down to 5°C and A.
utahensis to 10°C whereas the authoritative Agaves, Yuccas
and related Plants by Mary and Gary Irish lists them as tolerant
to -9°C, -29°C and -23°C respectively. Furthermore they list
as many as 20 Agaves which are tolerant of temperatures lower
than -10°C! Hmmmm... It would therefore appear that if provided with
the appropriate summer temperature, sufficient light and suitable soil
some of these plants would be fully hardy not only in the U. K. but also
in Eastern Europe. There is a similar story with Aloes where,
for example, some forms of Aloe variegata tolerate temperatures
down to -8°C (Guide to the Aloes of South Africa, Ben-Erik
van Wyk & Gideon Smith, 2nd edn 2003) where the RHS book suggests
10°C. Van Wyk and Smith also note that “Aloe aristata
is very cold hardy. It occurs naturally in some of the coldest parts of
southern Africa, in the central Karoo and in the mountains of Lesotho.”
The RHS book suggests a minimum of 10°C for this plant whereas -10°C
would seem more reasonable. There is little wonder that very few gardeners
bothered to try these plants outside.
the matter is no different. The now very popular Jelly Palm Butia
capitata (RHS minimum - 0°C for short periods only) is described
as follows by Robert Lee Riffle and Paul Craft (An Encyclopedia of Cultivated
Palms, 2003): “being adaptable to zones 8 through 11 in drier climates”
i.e. to temperatures down to minus 12.2°C. Phoenix canariensis
(the Canary Date Palm) takes similar temperatures when its minimum is
given as 10° to 16°C by the RHS Encyclopedia. More of these examples
can easily be found. Again, a very large Hmmmm….
reason is that exotic plants are both more widely available and much cheaper
than they were as little as ten or fifteen years ago. This encourages
experimentation by lowering its cost. It has certainly made me far less
nervous when trying out something new.
and perhaps very significantly, a large exotic planted one year may not
live to see the following year or, if it does, it may be in rapidly declining
health and size after a typical U. K. winter. As observers, all we know
is that it has been planted by somebody in his garden – we do not
know when (perhaps yesterday?) nor do we know what will happen to it during
the coming winter – and we likely to assume that it has been growing
in that position for some time and will continue to do so successfully
in the foreseeable future. I have heard of a man who bought Bismarckias
several years in a row in order to replace the previous year's defoliated
and probably rotting stumps. Bismarckias are not cheap plants.
I suppose you could call this 'extreme bedding' in the manner of 'extreme
sports'. The plants we see and admire are often the ones which have not
(yet) imploded or undergone wintertime meltdown.
common reason for the increasing number of exotics in our gardens is the
enthusiasm of some garden centre and nursery staff who, as already mentioned,
talk customers into buying often unviable exotics on the grounds that
'climate change ensures that soon it will be much warmer' (I wonder when;
perhaps next month?). Most people do not need much convincing and are
happy to walk away with plants that remind them of their last holiday
in the Caribbean. The following year they may be back for replacements
or may soon begin to treat such plants as annual bedding.
other factors which may have more local effects. I am thinking in particular
about the 'urban heat-island effect' (this refers to the way in which
large agglomerations tend to produce local heat). The higher the temperatures
of the insides of the buildings, the higher become the temperatures outside
- all other things being equal, of course. London is often quoted as a
model example but this effect is present in all urban areas of substance.
Over the years - certainly over the last fifty or so years - with the
increased levels of heating the urban heat island effect is bound to have
become more significant and has enabled slightly more tender plants to
grow in places where none grew before.
word of caution. The unwary may suggest that early-flowering varieties,
with which they are unacquainted, indicate that the temperature must be
rising. Such comments have often been made to me when visitors noticed
early-flowering Narcissi in spring. In fact, early-flowering
in many spring plants may well be the result of a bad previous summer
and autumn (with lower temperatures) rather than of higher overall temperatures.
This was certainly the case at Southern Comfort at the beginning of 2009.
Indeed, the flowering of Narcissi seems to be brought on by by
cold spells rather than by warm ones.
Even if we
treat some of the predictions of temperature rise seriously the rate of
increase is minute in terms of its effect on plant life - a rise of a
fraction of a degree in our lifetime is hardly a reason to worry about
what we are going to plant in our garden in ten years time, let alone
next season. Some gardening web sites (e.g. http://www.myglobalgarden.com/blog/)
even seem to present a picture of global warming as a fait accompli.
The whole matter is no less than a contagious mass hysteria based on a
deep guilt about being human and breathing out carbon dioxide. As for
me, I would welcome a few degrees of warming but I would be a fool if
I put my money on it.
is another side to this peculiar 'debate'. When I was a schoolboy I was
taught about photosynthesis — a process occurring within green plants
whereby carbon dioxide and water react together under the influence of
sunlight in order to produce carbohydrate and oxygen. The carbohydrate
is essential for energy production and growth within the plant and in
turn enables animals, all of which are dependent on plants, to exist.
In simple terms, CO2 helps the plants to grow. So, within
limits, the more CO2 we have in the atmosphere, the better
plants will grow. All gardeners ought to take note.
March 2009, last revision January 2011)
have been much encouraged by the large number of people who have
been following up the links listed below. The NGS, it would appear,
has also jumped on the alarmist bandwagon. In issue 4 (autumn 2009)
of their newsletter the NGS has included an article which suggests
that when we use peat we increase emissions of carbon dioxide. This
is nonsense because all organic plant materials have a
similar chemical composition to peat and decompose in similar ways.
So using other types of organic compost will have the same effect.
it is unsound to say that peat should be left in situ because
it absorbs carbon dioxide. Peat either in situ or elsewhere
most certainly does not absorb carbon dioxide in any meaningful
sense of the word. It is the sphagnum moss growing on top of peat
in acid bogs that absorbs carbon dioxide before it becomes itself
converted to peat. However, sphagnum moss is not unique in doing
this - all living plants do this and most are probably more efficient
at it than sphagnum moss. So this is more nonsense.
this is probably quite irrelevant anyway because the relationship
between carbon dioxide concentration in the atmosphere and temperature
rise is yet to be established (some scientists say that there is
very little, or even no simple or direct, correlation) as is the
question of whether increases in carbon dioxide are damaging to
life on this planet - so far the evidence of the latter points in
the opposite direction.
interesting facts about global warming , climate change &
happened to Global Warming?' is the title of an article which
appeared on the BBC web site in October 2009. A quick and easy
digest stressing the most important fault in the hypothesis of
Global Warming: why do global temperatures not rise as the concentration
of carbon dioxide in the atmosphere rises? 'What happened to Global
just aren't going to know what snow is." So said Dr David
Viner, a senior research scientist at the climatic research unit
(CRU) of the University of East Anglia in the year 2000. Most
of the world, it seems, believed him then. The tragedy is they
still believe him now. One such incorrect prediction normally
sends the most carefully thought out scientific hypothesis to
all about what he and others said at the time.
earth's core itself produces a massive amount of heat which gradually
dissipates at the surface. Geothermal heat keeps Iceland warm,
melts ice caps and heats the Arctic. http://www.iceagenow.com/index.htm
stone-age man had cared about the future we would now have a heap
of flints the height of Mount Everest.
now or be damned!' This warning is as old as our civilisation:
pestilence, plague, famine, nuclear holocaust, ozone holes, amalgam
tooth fillings, global cooling, meteors, bird 'flu', swine 'flu'
and now global warming.
you don't believe any of this then check it elsewhere on the internet
or any other sensible place. You may well be very surprised by
what you find. And if you still think that humans are responsible
for global warming or that global warming must be a bad thing
you will believe in fairies.
Great Global Warming Swindle - A documentary (DVD),
Martin Durkin, WagTV, 2007 (WAGtv0005) Apocalypse? No! - DVD of Christopher Monckton explaining
why global warming is not a crisis, 2007.
Vaclav Klaus Blue Planet in Green Shackles - What is
endangered: Climate or Freedom Competitive Enterprise
Institute; 1st edition (2007).
David J.C. MacKay Sustainable Energy - Without the Hot
Air UIT Cambridge Ltd (2009) - http://www.uit.co.uk/content/sustainable-energy
Patrick J. Michaels and Roberty C. Balling Climate of
Extremes - Global Warming Science They Don't Want You to
Know Cato Institute 2009.
Nigel Lawson An Appeal to Reason - A Cool Look at Global
Warming Duckworth Overlook 2008.
Roy Spencer Climate Confusion: How Global Warming Hysteria
Leads to Bad Science, Pandering Politicians and Misguided
Policies that Hurt the Poor Encounter Books 2008.
Lawrence Solomon The Deniers: The World Renowned Scientists
Who Stood Up Against Global Warming Hysteria, Political
Persecution, and Fraud - And those who are too fearful to
do so Richard Vigilante Books 2008.
Christopher C. Horner Red Hot Lies: How Global Warming
Alarmists Use Threats, Fraud, and Deception to Keep You
Misinformed Regnery Publishing 2008
Christopher Booker's regular column in The Sunday Telegraph
Videos Christopher Booker, writing in the Sunday Telegraph (29
November 2009) described the revelations resulting from the e-mail
hack at the Climate Research Unit, at the University of East Anglia,
as showing 'the
greatest scientific scandal of our age'. This may yet prove
to be an understatement. Here are some comments from across the